Scientific research has shown that the human body functions to the pace of an internal biological "clock". This clock, or circadian pacemaker as it is known in the art, is located in the brain and is regulated by exposure to natural or artificial light.
It has been found that humans tend to exhibit different degrees of alertness at different phases in their circadian cycle. Often, the activities in which humans wish to engage do not coincide with the most appropriate points in their cycle. Recent research indicates, however, that a subject's circadian cycle may be adjusted or shifted to better correlate the cycle with the subject's desired lifestyle.
Because the circadian cycle is regulated by light, exposure to carefully timed, high-intensity light is effective in adjusting the circadian phase by altering body temperature and secretion of the light-sensitive hormone melatonin. Additionally, exposure to high-intensity light has been found useful in treating certain psychiatric disorders (such as seasonal affective disorder and depression), jet lag, and chronic fatigue associated with "shift work" or the like.
U.S. Pat. No. 5,163,426 issued Nov. 17, 1992 to Czeisler et al. (Ser. No. 07/066,677, filed Jun. 26, 1987) discloses a lighting system for adjusting the circadian cycle. The system disclosed in this patent consists of large banks of fluorescent tubes or incandescent bulbs assembled within light "boxes" or "screens", or on adjustable stands, or illuminated goggles having small internal lamps. Although this system is capable of effectively adjusting the circadian cycle, it requires a large amount of energy, produces a significant amount of heat, and is not necessarily transportable.
In an effort to overcome the transportability and heat problems, light masks and other types of portable light systems to be worn on the head have been developed. One such example is disclosed in U.S. Pat. No. 4,858,609 to Cole. The Cole patent discloses a bright light mask having a reflective filter which minimizes heat delivery from the light to the user. The mask of the Cole patent, however, completely covers the eyes and does not allow the user to see. Obviously, this is not acceptable for individuals whose optimum treatment time is during the day when they must engage in other sight-requiring activities. Moreover, the mask of the Cole patent utilizes an incandescent bulb or green light emitting diode which produces a relatively low lux of light. Accordingly, the mask must be worn for long periods of time in order for the light treatment to be effective. This long treatment period may also be inconvenient for those whose optimum treatment time is during the day.
U.S. Pat. No. 4,911,166 to Leighton et al. discloses delivering light from an incandescent bulb to a patient's eyes for treatment of seasonal affective disorder. The bulb of the device is affixed to a transportable, adjustable structure which is worn on the user's head. Although the device of the Leighton patent does not cover the user's eyes, it obscures the user's vision. Specifically, the incandescent bulb of the device is positioned immediately in front of the user's eyes thereby physically blocking the user's field of vision. Moreover, light radiated from the bulb is focused into a cone by a fresnel lens which then projects the light directly into the user's eyes. Because the light is projected into the eye in such a manner, the user's field of vision is obscured thereby inhibiting the user's activity, as he is incapable of seeing beyond or around the light. Further, the device of the Leighton patent generates a high amount of heat because it utilizes an incandescent bulb. Further, the lens of the device must be specifically positioned in relation to the eye in order for the treatment to be effective.
Some light delivery systems do allow the user to see when the device is in use. For example, the LIGHT VISOR.TM. by Bio-Brite, Inc. employs a visor worn above the eyes which does not obscure the user's field of vision. The Bio-Brite device, however, utilizes an incandescent bulb which is not capable of generating high-intensity light (i.e. light measuring greater than 4,000 lux). Thus, treatment periods via the Bio-Brite device may be unnecessarily lengthy. Further, because the light of the device is adjustable, the photometrics are imperfect for modification of the circadian phase, as light generated by the device may be improperly projected to the eyes of the user. Finally, the light generated by the Bio-Brite device is columnated (that is, the photons of light travel in parallel columns) which can be uncomfortable to the user's eyes.
Still other devices (such as those disclosed in U.S. Pat. Nos. 1,187,672, 4,794,496 and 4,911,166) are heavy and uncomfortable, or are awkward in shape and therefore interfere with the user's head and body movements.
It was with these problems in mind that the present invention was developed. Accordingly, a primary objective of the present invention is to provide a lightweight and portable light source capable of generating a high-intensity light which will accomplish modification of the human circadian cycle.
Another objective of the present invention is to provide a light source and delivery system which simulates naturally occurring overhead light entering a person's eyes.
Another objective of the invention is to provide a high-intensity light which does not produce and radiate a high amount of heat to the eyes of the user.
Still another objective is to provide a light producing and delivery system which reliably delivers light to the eyes of the user regardless of the position of the user's head.
Another objective of the present invention is to provide a light producing and delivery system which affords the user maximum visibility by occupying a relatively small portion of the user's peripheral field of vision when the system is in use.
Yet another objective of the invention is to provide a light system which does not consume a large amount of energy.